The present invention relates to portable audio devices, and more particularly, to portable audio devices with control units that are detachable from a main unit.
Referring to FIGS. 7, 8 and 9, a typical prior art portable audio device 100 such as a compact disk (CD) player or tape recorder, has a main unit 10 with a main control panel 22. Main control panel 22 includes a main display 13 and main control actuators 12. Main control actuators 12 in, for example, a tape recorder, allow a user to control functions such as sound volume, tape stop, tape rewind and tape fast forward, etc.
An audio/control cable 15 transmits audio signals from main unit 10 and control signals from a remote control unit 14a. Remote control unit 14a has a remote display 21 and remote control actuators 17a. Remote control actuators 17a and remote display 21 perform at least some of the same functions as main control actuators 12 and main display 13 respectively. An audio cable 20 transmits audio signals from a first plug 23 to an earphone set 110. A second plug 16, insertable in main unit 10, allows audio/control cable 15 to be connected and disconnected from main unit 10. First plug 23, insertable in remote control units 14a and 14b, allows audio cable 20 to be connected and disconnected from remote control units 14a and 14b. A battery 18, in remote control unit 14a, powers devices such as a clock (not shown), to show time on remote display 21.
Referring to FIG. 9, main unit 10 may be used without remote control units 14a or 14b. In this case, first plug 23 is connected directly to main unit 10. Audio cable 20 transmits audio signals directly from main unit 10 to a pair of earphones 19. Main unit 10 is controlled by main control actuators 12.
Referring now to FIG. 8, one kind of remote control unit 14b, has no built-in display. However, there is no remote counterpart to main display 13. This permits remote control unit 14b to be smaller and less expensive than remote control unit 14a.
Referring, now, also to FIG. 7, like remote control unit 14a, remote control unit 14b has remote control actuators 17b which perform the same functions as main control actuators 12. Either of main control actuators 12 or remote control actuators 17b may be used to control main unit 10. Earphone set 110 is connectable to remote control unit 14b by first plug 23 as it is to remote control unit 14a.
When main unit 10 is used with earphone set 110 alone, main control panel 22 is necessary for control. But when remote control unit 14b is used with main unit 10, main control actuators 12 become redundant. This is because remote control actuators 17b perform the same functions as main control actuators 12. The redundancy is even greater when remote control unit 14a is used with main unit 10. In this case, main display 13 also becomes redundant. Such redundancies in control and display functions increase the cost, size and probability of breakdown of portable audio device 100.